Controlled engine exhaust gas recirculation is a known technique for reducing oxides of nitrogen in products of combustion that are exhausted from an internal combustion engine to atmosphere. A known EGR system comprises an EGR valve that is controlled in accordance with engine operating conditions to regulate the amount of engine exhaust gas that is recirculated to the induction fuel-air flow entering the engine for combustion so as to limit the combustion temperature and hence reduce the formation of oxides of nitrogen.
It is known to mount EGR valves on engine intake manifolds where the valves are subject to a harsh operating environment that includes wide temperature extremes and vibrations. Stringent demands imposed by governmental regulation of exhaust emissions have created a need for improved control of such valves. Use of an electric actuator is one means for obtaining improved control, but in order to commercially successful, such an actuator must be able to operate properly in such extreme environments for an extended period of usage. Moreover, in mass-production automotive vehicle applications, component cost-effectiveness and size may be significant considerations. An EGR valve that possesses more accurate and quicker response can be advantageous by providing improved control of tailpipe emissions, improved driveability, and/or improved fuel economy for a vehicle having an internal combustion engine that is equipped with an EGR system. A valve that is more compact in size can be advantageous because of limitations on available space in a vehicle engine compartment. It should also be possible to attain further economies and benefits by more fully integrating EGR valves with intake manifolds.
Hydrocarbon emissions from automotive vehicles are also subject to strict governmental regulations. It is known to associate a vapor collection system with a vehicle's fuel storage system. Volatized fuel from a fuel tank is temporarily stored in a vapor collection canister. At times, the collected fuel vapors are purged to the engine intake manifold via a canister purge valve. There, vapors entrain with combustible mixture flow into the engine where they are combusted. Precise control of purge flow is important in complying with relevant regulations and obtaining proper engine operation. Accordingly, it is also known to utilize pressure compensated, electrically controlled canister purge valves. It is believed that integration of a canister purge valve with an engine intake manifold can provide certain economies and advantages.